Not all of the vents in my house seem to be working properly, and my thermostat sometimes is set higher, then what the

house temperature reads. Examples: Thermostat gets turned to 68 and 5 hours later, it says it is 63 in here. I can feel heat coming out of some vents, but not others, or else it felels like cooler air coming out. I just had a new circuit board put in three years ago, nothing is obsturcting the vents and I did check to make sure they were all open. Any suggestions? I am tired of freezing in the smaller of two bathrooms, and a couple of other rooms. HELP!!!

There are many things that can cause the house not to properly heat.
If return ducts are located or supply for that matter were they are exposed to outside air temps, this will prevent the entire system from properly heating.
A incorrectly set up thermostat can also cause all sorts of issues.
A messed up circuit board or one that is not proper for the system it was installed in can cause short cycling of the blower, the gas valve, all sorts of issues.
As KMS said dirty filters or a blockage in the ducts can be something to consider. However I doubt the duct is blocked unless perhaps yours are lined on the inside.
A large balancing damper also can cause issues. If the damper closed down, but still reads open can cause all sorts of problems.
The thermostat location and the way its mounted can also be problematic. If the wall behind the thermostat has air flowing through it, perhaps cold or warm air it can mess up the readings and cause issues. If the thermostat is not properly set up for the fuel system and the enthalpy setting is wrong in it. The house will remain cold all the time.
Poor duct design is still another issue. Poor installation practices or really old systems oftentimes fails to deliver the air.
A short cycling of the furnace will keep air temps down.
The very first thing I would ask, Did the system ever work right in the past? I know as someone who has done this work for years. Many HVAC contractors reinvent the engineering of both residential and commercial systems in order to up sell people into products that they do not need or want. Way to many of these arm chair engineers sell products and services that completely change the way the system was designed to work. Once that occurs the client who is not happy goes to another contractor who again changes it in an effort to make it work. If they ever simply put it back the way it was when it was first designed. The issue can be solved.
As an airplane pilot, one of the very first things we learn when we start out is. If you turn off a switch, or turn a dial and it gets real quite in the plane. Put that switch or dial right back were you found it so it becomes noisy again. This holds true with any home improvement project. If you change anything and the outcome is not what you expected simply put it back and try something else. In your case, did the issues begin when they changed the circuit board?

KMS & Woodbridge - my heating system seemed to be working fine until 2 or three weeks ago. I switched to 3M filters aroung Dec. 1st, and the filter looks fine. I did notice today that one air return vent in the first floor bedroom was closed though. I opened it. Maybe that was the culprit. I don't really understand how an air return vent could affect air coming out of the vent, but that's ok. I have never changed any settings, etc for where the thermostat was insltalled, and as stated above, my circut board is only three years old. Windows are covered, except in one second floor bedroom, b/c I like a cooler bedrroom to sleep in. I will give it another couple of days and see if I need to get someone to scope it for a damaged duct. Thanks for your input, and if I need more help, I will contact ya'all.

If you used the new HEPA type 3M filter and things started to go wrong, put the old type back. Remember my airplane comment in prior post. Ideally return air vents should remain open, but that will have no real bearing on the thermostat issues or the bathrooms. I got your email as well.

I'm EXTREMELY familiar with freezing even when the heat was running. We had an 1898 victorian in MA before moving here in Dec 2009--5600 sq ft house, 5 zone gas forced hot air system. I had your problem in 1 zone, and it was a bad thermostat. We finally put in a new one and that rectified the problem....we still froze though...damn old joint leaked like a sieve!! Beautiful, jawdropping house, but completely uncomfortable 8mos a year!!

Well, I suspect our problem is our substandard system. The house was built in 2001 and the system is the original one. It went through foreclosure twice before we bought it and sat empty for a long time. The system has NEVER worked properly since we moved in. Every summer we must have someone come out and put in more freon because we have a small leak. We've lived here since 2008 and every year we've had to have some kind of work done on the unit. Once we can afford a new unit, I plan to have the duct work checked too to make sure it's in good condition and located properly. Too bad, Woodbridge, you aren't in Middle TN. You sound like you know what you're doing and I'd hire you in a heartbeat! :)

Karen, the very first thing you want to do, is to get a home energy audit performed. It is very common for that age home to have a lot of air leakage, very poor insulation and undersized duct systems or incorrectly sized ducts.
In addition, if the AC system is located in the attic, you may want to consider insulation on the roof (foam) to bring the system into the heating/cooling zone. This in effect will lower the capacity needed in many cases by at least one ton or 12,000 BTU. What this means to you is a smaller system to do the same size house, more comfort, and way less cost to operate. Payback is a short 5 to 8 years in many cases. Combined with many incentives that the state and the energy star program offers, your combined costs utilities from energy use, and the loans you need to get if you do not pay cash for the upgrades, should be less then your paying now for the system the way it is in just operation costs alone.
Also you want the contractor, whoever it is that you use to do two things, and if they say they do not need to do them, find another. A manual J which is a heat load form and a manual D which is a duct sizing form that tells then exactly what size ducts are required to properly heat and cool the room as far as delivery of air is concerned.

We replaced all the windows in our house and it holds the heat a lot longer with fewer cold spots. The contractor that built this house use expando foam around the windows and nailed all the flanges which didn't allow for any settling or expansion/contraction of the house. This broke the seal of the double paned windows. Our neighbor had her ducts scoped and found that 2 of the upstairs ones were 60% blocked with construction debris. Same contractor.

I found another reason today for the cold - it seems that when my house settled, it caused some off the window frames not to quite fit. If I open the bottom window to get fresh air in, the upper one lowers a little bit too. It looks like it is still in its proper place, but it wasn't, and was allowing a little cold air to come in. I went around the house, making sure every window was completely closed & sealed. That was a few hours ago, and I am already noticing a difference when I am on the first floor. Who knows? Maybe tha was the problem all along....